This disclosure is directed to a method for the manufacture of salts of hydroxy-substituted aromatic compounds, particularly to the manufacture of alkali metal salts of hydroxy-substituted aromatic compounds. The disclosure is also directed to the manufacture of polyetherimides from the prepared salts of hydroxy-substituted aromatic compounds.
Salts of hydroxy-substituted aromatic compounds find varied uses in the industry. For example, bisphenol dialkali salts can be used for the synthesis of polyetherimides via displacement polymerizations.
The existing methods to prepare bisphenol dialkali salts typically use a significant amount of azeotropic solvents such as xylenes, ortho-dichlorobenzene, or toluene in order to remove water, either produced as a byproduct of the reaction, or present in the reaction mixture as a solvent or co-solvent, through azeotropic distillation. To reduce cost, it would be desirable to avoid using azeotropic solvents in the process. Accordingly, there exists a need for a simplified method to prepare salts of hydroxy-substituted aromatic compounds without using azeotropic solvents.